The data reported in this paper are the result of subsequent studies of mechanics of breathing in normal infants during the first week of life. The purpose was t o provide further information concerning the development of respiration during the neonatal period after the onset of respiration and the first minutes' adaptation t o extra-uterine life. Thus, this study is to be considered as a continuation of a previous one devoted t o the first minutes of life and the onset of respiration [S]. The studies herein reported consists of the assessment of the mechanical properties of the lungs (lung compliance, pulmonary flow resistance) and work of respiration.
MaterialTwenty-three newborn infants were studied. Among these were 10 in whom the onset of breathing was reported previously [8]. Nineteen of the infants were fullterms with a range of birth-weight between 3100 and 4499 g, five (Nos. 26, 78, 84, 85, 86) were prematures according to their birth-weights